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Biomedical subjects

R Roubin

Publications and source records attributed to R Roubin.

At least 37 records · Page 2Linked to original sources
PubMed1982

Release of platelet-activating factor (PAF-acether) and leukotrienes C and D from inflammatory macrophages.

Macrophages (M phi) isolated from the peritoneal cavity of C57BL/6 mice were either untreated or treated with various eliciting agents (thioglycollate, sodium caseinate) or with an activating agent bacillus Calmette Guérin (BCG). The various populations were assessed for their ability to release platelet-activating factor (PAF-acether), an ether phospholipid mediator, and slow-reacting substance (SRS), a lipoxygenase arachidonic acid derivative. PAF-acether was recovered in higher amounts form BCG M phi than from resident M phi, whereas elicited M phi exhibited a marked decreased ability to release this mediator. Such variations were only quantitative as evidenced by the similar enzyme sensitivity and high pressure liquid chromatography (HPLC) retention times of the various PAF-acether-containing supernatants. Resident, BCG- and sodium caseinate-induced M phi released similar amounts of SRS, whereas thioglycollate M phi exhibited once again a marked decreased ability to release this mediator. Comparing retention times on HPLC of resident and BCG M phi SRS with those of synthetic leukotrienes C and D, molecular variations were noted. Even though both M phi populations released higher amounts of leukotrienes C than D, the D/C ratio was higher in BCG M phi than in resident M phi. These results show that different environmental factors can influence the release of PAF-acether and leukotrienes from M phi.

Animals↗
PubMed1982

Lymphoid cells in lymph nodes and peripheral blood of patients with squamous cell carcinoma of the head and neck.

Fifty-five patients with squamous cell carcinoma of the head and neck were evaluated immunologically by measuring the level of T cells (E-RFC) and high affinity subset T cells (E-29) in the peripheral blood and peritumorous lymph nodes. A significant decrease (p less than 0.05) in mean percentage of E-29 was observed in cancer patient peripheral blood. In peritumorous lymph nodes, there was no difference in terms of total T cells or of high affinity subset T cells, as compared to non-malignant lymph nodes, or between tumor-free and metastatic lymph nodes. Macrophage content was much higher in metastatic than in tumor-free lymph nodes (p less than 0.05) and these macrophages frequently appeared to be more active when tested in phagocytosis of sheep red blood cells sensitized with IgG or IgM + C.

Acid Phosphatase↗
PubMed1982

Release of platelet-activating factor (PAF-acether) and 2-lyso PAF-acether from three cell types.

The release and formation of PAF-acether and of its deacetylated precursor (2-lyso PAF-acether) have been determined on mouse macrophages (M phi), human polymorphonuclear neutrophils (PMN) and rabbit platelets using specific secretagogue stimuli in the same experimental conditions. It was found that as opposed to M phi, PMN and platelets were good releasers of PAF-acether. However, the total amount of PAF-acether formed by M phi and PMN was larger than that formed by platelets. The total amount of 2-lyso PAF-acether varied also for the three cell types, with platelets being by far the best producer. Calculation of the amount of PAF-acether formed from 2-lyso PAF-acether indicated that M phi and PMN possess a higher acetylating ability than platelets.

Animals↗
PubMed1982

Biosynthesis of platelet-activating factor (PAF)acether). III. Formation of PAF-acether from synthetic substrates by stimulated murine macrophages.

Rat adherent macrophages (M phi) isolated from 2.5 x 10(6) peritoneal cells release 5.7 +/- 1.3 ng/ml platelet-activating factor (PAF-acether: 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine) when stimulated by zymosan (Z). The yield of PAF-acether was increased to 13.8 +/- 1.8 ng/ml when stimulation occurred in the presence of 0.1 mM acetyl-CoA. That M phi used the acetyl moiety of acetyl-CoA to increase PAF-acether biosynthesis was demonstrated by the following criteria 1) as opposed to sodium acetate, malonyl-CoA, butyryl-CoA, palmitoyl-CoA, and CoA were inefficient in increasing the yield of PAF-acether; 2) radiolabeled PAF-acether was obtained after exposure of Z-stimulated M phi to 3H acetyl-CoA; actually, both radioactivity and biologic activity were eluted from HPLC with the same retention time as synthetic or natural PAF-acether; 3) after treatment with phospholipase A2, both radioactivity and biologic activity disappeared from these fractions. The yield of PAF-acether was further increased to 23.6 +/- 2.9 ng/ml by adding 0.5 microM totally synthetic 2-lyso PAF-acether (1-O-octadecyl-sn-glyceryl-3-phosphorylcholine) to Z-stimulated M phi cultured in the presence of acetyl-CoA. Again, using 3H 2-lyso PAF-acether, the formation of radiolabeled PAF-acether could be demonstrated. These results indicate that an acetyl-transferase is capable of synthesizing PAF-acether from 2-lyso PAF-acether and acetyl-CoA in intact M phi.

Acetyl Coenzyme A↗
PubMed1981

Is platelet-activating factor (PAF-acether) synthesis by murine peritoneal cells (PC) a two-step process?

PAF-acether (1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine) is released from several cell sources simultaneously with an inactive non-acylated compound (1-O-alkyl-glyceryl-3-phosphorylcholine) (lyso-PAF-acether). Formation of the latter probably results from the activation of a phospholipase A2 (PLA2). Indeed, the PLA2 inhibitors, bromophenacyl bromide (BPB), mepacrine, 874CB (100 microM), and EDTA (5 mM), blocked the zymosan-induced release of PAF-acether from PC. EDTA and BPB also markedly reduced the release of lyso-PAF-acether. To verify this hypothesis, acetyl coenzyme A (acetyl-CoA) was added to stimulated PC. This enhanced the release of PAF-acether in a dose-dependent fashion from 1 microM acetyl-CoA to reach a maximal increase - 200% - at 100 microM. Furthermore, using 3H acetyl-CoA, incorporation of labelled acetate into PAF-acether was suggested by (1) identical chromatographic patterns of biological activity and radioactivity; (2) disappearance of these activities after treatment with PLA2, but not after exposure to lipase from Rhizopus arrhizus. PAF-acether was also obtained when both acetyl-CoA (100 microM) and synthetic lyso-PAF-acether (0.2 microM) were added to unstimulated PC previously treated with BPB (100 microM for 10 min). These results suggest that the release of PAF-acether is the consequence of at least two different steps: (1) hydrolysis of 1-O-alkyl-2-acyl-glyceryl phosphorylcholine by PLA2; (2) enzymatic acetylation of the hydrolysis product.

Acetophenones↗
PubMed1981

Release of leukotrienes C (LTC) and D (LTD) from inflammatory macrophages during phagocytosis of zymosan and bacteria.

Release of slow-reacting substance (SRS) was obtained from resident mouse peritoneal macrophages (R-M phi) upon stimulation with phagocytic stimuli (zymosan, bacteria). The release of SRS from thioglycollate elicited M phi was impaired, whereas that from BCG-elicited M phi was quantitatively unaffected. However, using a high pressure liquid chromatography separation procedure, qualitative variations between SRS released from R-M phi and BCG-M phi were observed. In both cases, LTC was the major component released from M phi, but greater amounts of LTD were released from BCG-M phi than from R-M phi. These data indicate that local environment alters leukotriene generation by M phi.

Animals↗
PubMed1979

Markers of macrophage heterogeneity. I. Studies of macrophages from various organs of normal mice.

A unique subpopulation of macrophages (M phi) was identified among the spleen and bone marrow M phi of normal mice. After 24 h of culture, approximately 2.5% of the adherent cells cluster into "foci" of 10-30 cells. On the basis of their phagocytic and morphologic characteristics, these focus-forming M phi (FF-M phi) appeared to be highly activated. Uncoated sheep erythrocytes (E) were ingested by FF-m phi indicating that opsonization was not a prerequisite for phagocytosis. However, IgM-coated E (EIgM) were more readily phagocytosed by FF-M phi than were E suggesting that IgM is recognized as an effective opsonin by these cells. EIgM and E coated with IgM and complement (C) (EIgMC) were ingested by approximately the same percentage of FF-M phi; thus, if these cells possess complement receptors in addition to structures which bind EIgM, the C receptors do not enhance the ability of FF-M phi to ingest opsonized particles. The non-focus-forming M phi, e.g. individual M phi (I-M phi), in the spleen and bone marrow can, themselves, be divided into various subpopulations distinguished by their ability to bind and ingest E, EIgM ana EIgMC. These may represent various subpopulations of M phi or M phi at various stages of activation or differentiation. While spleen and bone marrow M phi contained FF-M phi and I-M phi which vary in their ability to ingest E, EIgM and EIgMC, theM phi of the peritoneum and blood of normal mice were far more homogeneous. Peritoneal and blood M phi did not form foci, ad did not ingest E or EIgM in significant amounts although a small percentage were able to ingest EIgMC. These data suggest that the population of M phi in the spleen and bone marrow are far more heterogenous than those found in the peritoneum or blood and that binding and phagocytosis of various coated and uncoated erythrocytes can be studied to elucidate this heterogeneity.

Animals↗
PubMed1975

Characterization of the mononuclear cell infiltrate in human malignant melanoma.

In the skin infiltrate of superficial spreading melanoma, non phagocytosing mononuclear cells (NPMC) represent a major cell component. The number of NPMCs decreases as a function of tumour progression. In addition, when an NPMC is in contact with a malignant melanocyte, the latter cell exhibits ultrastructural degenerative changes. In the blood of healthy donors and of melanoma patients, atypical mononuclear cells (AMC) can be identified. AMCs have been shown to participate in antibody-dependent cellular cytotoxicity (ADCC) reactions against melanoma cells in vitro. In this paper, it is reported that NPMCs and AMCs have in common their size, and some ultrastructural features such as indented nuclei, dispersed organelles, rough endoplasmic reticulum profiles and surface microvilli. The two cell types are negative for non-specific esterase. They also fail to react for peroxidase at either the light or the electron microscopic level. They do not adhere to glass. AMCs do not form spontaneous E rosettes, they have no surface IgG and they have no receptors for complement. However, they do form rosettes with EAIgG. On frozen sections firm binding of EAIgG has been seen on the skin infiltrate in three cases out of 10. It is concluded that NPMCs might react with tumour cells in vivo, in the same manner as do AMCs in vitro.

Cell Membrane↗
PubMed1975

Cell-mediate cytotoxicity in vitro of human lymphocytes against a tissue culture melanoma cell line (igr3).

Purified peripheral blood lymphocytes from 13 healthy donors, 6 melanoma patients and 1 halo nevus patient were tested for cytotoxic activity against an allogeneic melanoma cell line (IGR3) in, at least, one of the following assays: cell-mediated cytotoxicity (ADCC) and microcytotoxicity assays (ma). The lymphocytes were isolated by Ficoll-Triosil gradient centrifugation (fraction F) followed by removal of iron-phagocytosing and adherent cells (fraction FFF) and by subsequent passage through anti-IgG columns (fraction FFF-C). Leukocytes of each fraction were identified by different methods including morphology, rosette-formation, phagocytic activity, and membrane fluorescence. CMC activity paralled ADCC activity at a log lower level of sensitivity. In both assays lymphocytes of fractions F and FFF had the highest activity, whereas in fraction FFF-C cytotoxicity was strongly reduced. In all three lymphocyte fractions CMC and ADCC activity could be blocked by preincubation of the effector cells in aggregated IgG. Furthermore, depletion of E rosette-forming lymphocytes slightly increased ADCC and CMC activity, whereas depletion of EA and EAC rosette-forming lymphocytes strongly decreased it. Our results therefore indicate that in both CMC and ADCC assays, non-adherent, non-phagocytic Fc receptor-bearing lymphocytes ("K" cells) were the active cytotoxic cells. In MA, on the other hand, mononuclear phagocytes seemed to be the most active cell population. So far no significant difference was observed in CMC, ADCC, and MA between control persons and melanoma patients

Animals↗